Huygens Wind Experiment Salvaged

← Back to Stories (view on slashdot.org)

Huygens Wind Experiment Salvaged

Posted by timothy on Wednesday February 9, 2005 @07:53AM from the savaged-comes-later dept.

SeaDour writes "Earlier, it was reported that the data from a critical wind speed experiment onboard the Huygens probe to Titan was completely lost due to someone forgetting to turn on one of Cassini's communications channels. However, it now appears that ground-based radio telescopes from the National Radio Astronomy Observatory were able to record the transmission's many subtle doppler shifts and reconstruct that lost wind data. The winds altered the probe's horizontal rate of descent, thereby producing a change in the frequency of the signal received on Earth. Additionally, the resolution of the radio telescopes was good enough to track Huygen's position to within one kilometer, allowing for the creation of a three-dimensional model of Huygen's descent."

26 of 207 comments (clear)

backup by j1bb3rj4bb3r · 2005-02-09 07:55 · Score: 3, Insightful

... nothing like a little backup.

--
*yawn*
You know whats really funny by suso · 2005-02-09 07:55 · Score: 3, Insightful

is that if that experiment would have been turned on like it was supposed to, probably nobody here would have ever known that it existed in the first place. ;-)
Horizontal rate of descent by DemiKnute · 2005-02-09 07:55 · Score: 3, Funny

How can you have a horizontal rate of descent? Was this thing was falling sideways?

What a strange and fantastic world this Titan must be.

--
.
1. Re:Horizontal rate of descent by BradleyUffner · 2005-02-09 07:58 · Score: 3, Informative
  
  It was descending at an angle due strong winds. It's rate of descent could be something like 2ft of horizontal movement for every foot of vertical movement (numbers made up on the spot). It's sometimes called a Glide Ratio.
2. Re:Horizontal rate of descent by Mattcelt · 2005-02-09 09:06 · Score: 4, Informative
  
  It's just you. ;-)
  
  Seriously, if you think about it, this makes perfect sense. The Earth is a rotating sphere, right? So unless an object approaching ground level happens to maintain a perfectly geosynchronous orbit around the Earth as it falls inward, it will hit the atmosphere at an angle and not straight down. So almost inevitably, there will be a horizontal component (think the base of the triangle where the trajectory/vector is the hypotenuse) to go with the vertical component. How much and in which direction(s) the object is deflected from its ordinary horizontal state (the result of the pure angle of entry into the atmosphere) gives direct indication about the presence, speed, and direction of any wind which might exist at that place. (Vertical deflection from standard gravitational acceleration gives important information about the stratification and density of the atmosphere in the same manner.)
  
  Does it make more sense now?
Things like that just amaze me... by Dutchmaan · 2005-02-09 07:57 · Score: 4, Interesting

That we have equipment sensitive enough to track a probe's position to within *1* km all the way out on Titan..

saying it seems rather bland but when you think of how many millions of miles away it is, I think it's pretty remarkable.
1. Re:Things like that just amaze me... by another_henry · 2005-02-09 08:04 · Score: 5, Informative
  
  The original experiment using Cassini's onboard receivers would have had an accuracy of better than 1 m/sec and presumably similar positioning accuracy. Still, the probe accomplished a lot and was several different kinds of awesome.
  
  --
  "Studies have shown that people who eat peanuts live longer than those who do not eat."
2. Re:Things like that just amaze me... by LucidBeast · 2005-02-09 08:09 · Score: 5, Funny
  
  It's one of those moments when you realize that you are living in a Star Trek episode. You know when something goes wrong and then one of the guys (I forget the names) goes like "Captain, I can compensate using *strange word* to modulate *strange word* ...".
3. Re:Things like that just amaze me... by brainstyle · 2005-02-09 08:20 · Score: 3, Insightful
  
  That we have equipment sensitive enough to track a probe's position to within *1* km all the way out on Titan. when you think of how many millions of miles away it is, I think it's pretty remarkable.
  There we go again, mixing imperial and metric. When will we ever learn?
  
  --
  "Why can't everyone just be straight with me?"
  "Because we live in a bendy world, dear."
4. Re:Things like that just amaze me... by EpsCylonB · 2005-02-09 08:20 · Score: 4, Funny
  
  "Captain, I can compensate using *strange word* to modulate *strange word* ...".
  
  Whats strange about using a neutrino generator to modulate a tachyon field to create a holographic reconstruction ?
5. Re:Things like that just amaze me... by david+duncan+scott · 2005-02-09 08:27 · Score: 3, Funny
  
  Yeah, it's a perfectly cromulent technique -- I used to do that back home to bulls-eye whomp rats in my T-16.
  
  --
  This next song is very sad. Please clap along. -- Robin Zander
6. Re:Things like that just amaze me... by Rei · 2005-02-09 08:47 · Score: 4, Funny
  
  Back in middle school, my first "word" program was a qbasic "Random Star Trek Episode Generator" that worked exactly like that ;) It normally tried to insert realistic sounding star trek technobabble - of course, I added in a few "funny" options it.
  
  Worf: "Captain, we're experiencing a cheap plot device in Sector 6. It seems to be the work of underpaid script writers."
  
  Or occasionally it would insert a:
  
  Picard: "Quick, we need an engineer on the bridge!"
  
  Bones: "Dammit, Jim, I'm a doctor, not an engineer."
  
  Picard: "Dammit, Bones, I'm not Jim!"
  
  --
  Dear Lord: One of your creatures may be hurt tonight. Please let it be the other creature.
7. Re:Things like that just amaze me... by ShortSpecialBus · 2005-02-09 09:27 · Score: 3, Insightful
  
  Just because we can do more amazing things doesn't make the first thing less amazing, heh. Personally, I'm impressed by them both.
  
  --
  //FIXME: Bad .sig
I bet they just taped... by Anonymous Coward · 2005-02-09 07:57 · Score: 4, Funny

...the scientist who forgot to switch the experiment on, making "wooshing" sounds into a mike. "We got the data back, nothing to be embarassed about here, no sirree!"
R.E.S.P.E.C.T. ! by selderrr · 2005-02-09 07:59 · Score: 4, Insightful

if anyone at nasa is dumb enough to read slashdot : you guys rock !

Seriously : most people would give up, blaming someone else. It takes a true fighting spirit to try and recover from what someone else has fucked up.

--
When will I end this grieving ? When will my future begin ?
1. Re:R.E.S.P.E.C.T. ! by selderrr · 2005-02-09 08:17 · Score: 5, Insightful
  
  oh puhlease... Must everyone always turn everything into a debate ? Okay, so what. congrats to ESA as well. My post was not about Nasa or esa or Uso or wtf... It's about people being persistent and believing in a solution and an outcome, no matter how big the problem may seem, and no matter how big the fuckup to work around.
  
  if it eases your xenophobia : I'm european as well.
  
  --
  When will I end this grieving ? When will my future begin ?
2. Re:R.E.S.P.E.C.T. ! by jmichaelg · 2005-02-09 08:20 · Score: 4, Informative
  
  Figuring out that the wind data was embedded in the radio signal was an NRAO accomplishment.
  It wasn't NASA, it wasn't ESA and it wasn't easy...
3. Re:R.E.S.P.E.C.T. ! by i41Overlord · 2005-02-09 08:23 · Score: 5, Insightful
  
  How come when Europe does something, people claim that's it's a great European accomplishment and everyone salutes them.
  
  However when the USA does something and people claim it's a great American accomplishment, people get offended and feel the need to knock NASA?
  
  It's almost as if the political climate on this forum supports the recognition of someone's feats only if they're considered an underdog?
is it plugged in and turned on? by jacksonai · 2005-02-09 08:02 · Score: 4, Insightful

that's the first diagnostic question I always ask when fixing something.

--
Like Sweepstakes? Try out my service @ http://www.yourpowersweeps.com -- Free 21 day trial, no cc needed.
Reading the doppler effect on the signal by psyklopz · 2005-02-09 08:07 · Score: 3, Interesting

So, the experiment itself wasn't saved. They just found another way to get the data (reading the doppler shift in the signal).

So, here's a good question: why did they need to include the equipment for the experiment in the first place?
Re:Eh? by worst_name_ever · 2005-02-09 08:16 · Score: 4, Insightful

The receiver on the Cassini spacecraft didn't get turned on, but some very smart chaps here on Planet Earth listened very hard using some very expensive equipment and managed to hear the faint transmissions from Huygens anyway. Does that make more sense?

--

In Soviet Rush, today's Tom Sawyer gets high on you.
And the other 100s of imatges??? by Air-conditioned+cowh · 2005-02-09 08:33 · Score: 3, Interesting

IIRC about half of the picures taken were relayed via the A channel and what we have seen is all B channel stuff only.

Any chance of reconstructing those images from the ground-based recordings of the A channel, or is the signal so weak that all that can ever be deduced is the carrier frequency, not any data?
Reminds me... by biglig2 · 2005-02-09 08:44 · Score: 3, Insightful

... of a maxim my team has tried to explain to our senior management many times, without sucess:

"Yes, we will always pull a miracle out of the hat for you when everything goes wrong. But, you should not write your plans with this as an assumption."

--
~~~~~ BigLig2? You mean there's another one of me?
Re:Do I understand this? by Rei · 2005-02-09 08:51 · Score: 4, Informative

A whole lot more than 10; read the Planetary Society's account of just what it took to get the data back:

http://www.planetary.org/news/2005/huygens_radio -t racking_0207.html

Plus, they didn't know that this would work beforehand.

--
Dear Lord: One of your creatures may be hurt tonight. Please let it be the other creature.
Teching the tech by jfengel · 2005-02-09 08:55 · Score: 4, Interesting

The Star Trek:TNG writer's manual called for you to use the word TECH every time you needed a word like that; they got their science advisor to fill it in later.

So you really would see scripts with "Captain, I can compensate using TECH to TECH..."

I can't help but think that the series would have been better if TECH hadn't been such a cop-out. Sci-fi is about people, not technology, but often it's about how people interact with technology. If you don't know anything about technology then it's just the way people interact with mumbo-jumbo.
Larger story: All data nearly lost by behindthewall · 2005-02-09 09:14 · Score: 4, Informative

This hasn't gotten as much coverage, but a design oversight nearly cost all Huygens data. Doppler shift was not accounted for in the signal decode process. The mission plan had to be rewritten to find an alternative flight path that reduced the Doppler shift to within the limited acceptable tolerances. Fortunately, Cassini's approach to Saturn was accurate enough that enough fuel existed to allow this while preserving the latter part of the existing flight plan.

Of course, in retrospect, maybe earth-based monitoring would have come to the rescue in this event, in an even bigger fashion.

"Titan Calling: How a Swedish engineer saved a once-in-a-lifetime mission to Saturn's mysterious moon"
http://www.spectrum.ieee.org/WEBONLY/publicfeature /oct04/1004titan.html

Sorry if this is a repeat. Slashdot's search 503-ed on me.